public ActionResult GetRelationsPartPartial(int categoryId, string partIdsString)
        {
            //Hämta relationer och uppdatera selectboxarna i Index.cshtml
            CategoryPartsViewModel model = new CategoryPartsViewModel();
            model = _methods.GetUpdatedModelForSelectList(categoryId, partIdsString);

            return View(model);
        }
        public CategoryPartsViewModel GetUpdatedModelForSelectList(int categoryId, string partIdsString)
        {
            var parts = _productService.GetPartsByCategoryId(categoryId).ToList();
            var partIds = partIdsString.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
            var list = new List<Part>();
            foreach (var part in parts)
            {
                list.Add(part);
            }

            foreach (var partId in partIds)
            {
                foreach (var part in list)
                {
                    if (_productService.GetPartById(int.Parse(partId)).CategoryId != categoryId)
                    {
                        if (!_productService.HasRelations(int.Parse(partId), part.Id))
                        {
                            parts.Remove(part);
                        }
                    }
                }
            }

            var catparts = new CategoryPartsViewModel();
            catparts.Id = categoryId;
            catparts.Name = _productService.GetCategory(categoryId).Name;
            catparts.Parts = new List<PartViewModel>();
            foreach (var part in parts)
            {
                catparts.Parts.Add(part.MapTo(new PartViewModel()));
            }
            return catparts;
        }